Method of and means for forming an elongated opening in a pipe or the like



Sept. 29, 1953 J. w. DOLBY METHOD OF AND MEANS FOR FORMING AN ELONGAIED OPENING IN A PIPE OR THE LIKE Filed June 2'7, 1951 INVENTOR .fl J" 0 1 61444 ATTORNEYS.

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Patented Sept. 29, 1953 METHOD OF AND MEANS FOR FORMING AN ELONGATED OPENIN LIKE G IN A PIPE OR THE John W. Dolby, Chicago, 111., assignor to Configured Tube Products Company, Chicago, 111., a corporation of Illinois Application June 27, 1951, Serial No. 233,898

2 Claims.

My invention relates to an improved method for forming an elongated opening with cleanly punched. longitudinal edges and inwardly bent end tabs.

In one method of removably securing objects to pipe or like supporting members, the object is provided with one or more spring clips which are received in elongated openings in the pipe. Each clip has a pair of complementary spring elements that extend beyond the width of the opening in the pipe but flex to retracted positions when the clip is inserted or removed to allow the clip to pass through the opening. Fastening devices of this kind may be used, for example, in a chair where the pipes form the legs and other support members to define a frame and the clips are afiixed to the seat, back, and other parts to be removably secured to the frame.

In order to use clips of the above-described type effectively, it is necessary that the pipe have an opening of rectangular shape and of a size and width capable of receiving the clip in a manner permitting a secure fastening. It is desirable that the longitudinal edges of the opening be cut in a clean fashion so that the protruding spring anchoring portions of the clip can snap underneath the adjacent walls of the pipe.

It is also desirable that the elongated openings provided to receive the spring clips be so formed that the clips may be centered over their respective openings and pushed into locking condition without actually sighting the clips over the openings. This desirable feature is dictated by the fact that the fit of the part (such as a chair seat) carried by the clips may be a blind fit where it is impossible or diificult to sight each clip over its hole.

In accordance with the present invention, an improved method of and means for forming elongated clip-receiving holes in pipe is provided. Briefly, th pipe is held between a pair of complementary pipe-supporting dies which define between them a transverse slot of a size and shape corersponding to the desired clip receiving opening. A punch is then placed in the opening and forced through the exposed Wall of the pipe to punch out the desired hole. In front elevation, the punch has a cutting face of peak formation. At the peak, the punch presents a transverse cutting edge of substantially straight line formation. This initial cutting edge, when it engages a pipe to be cut, by reason of its substantially straight cutting edge depresses the wall of the pipe trans- 2 versely along a line extending beyond the edge of the opening, laterally to th axis of the pipe. The remainder of the cutting edge of the punch is hollow ground so as to present a concave formation to cut the pipe wall along the length of the opening. The hollow ground formation provides cutting edges on each side of relatively sharp angular formation, and contributes to the formation of end walls including extending tabs which are curled in the cutting operation and which remain in the pipe at the ends of the opening at the completion of the operation. In this fashion indexing indentations and a hole having cleanly punched longitudinal edges are formed in the pipe in a simple, high speed, and inexpensive punching operation.

It is therefore an object of this invention to provide an improved method of and means for cutting elongated holes having inwardly bent end tabs and clean punched longitudinal edges in a pipe or the like.

It is a further object to provide an improved method of and means for cutting elongated holes having inwardly bent end tabs and clean punched longitudinal edges in a pipe or the like in a simple, inexpensive, fast manner.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view in elevation of a pipe having two openings formed by the apparatusand method of the present invention and with some parts broken away in axial cross-section to show more clearly the configuration of one of the openings;

Figure 2 is an end elevational view of the two complementary pipe supporting dies in their assembled position;

Figure 3 is a top plan view of one of the dies of Figure 2;

Figure 4 is a view in perspective of the punch used with the dies of Figure 2, the punch being in the inverted position to show more clearly its configuration; and, v

Figure 5 is a viewin elevation on the line 5-5, Figure 2, but with the punch and pipe in place, the punch being in the position of forming the indexing indentation.

Referring now to Figure 1, there is shown at In a pipe of mild steel, or similar material with a pair of openings 0, formed by the method and apparatus of the present invention, the left hand opening being shown in elevation and the right hand opening being shown in a broken away central cross-section. As will be evident from the drawing, each opening is. of elongated rectangular shape with cleanly punched longitudinal edges I: where the wall'of thepipeis cut in a substantially straight line so that the spring portion of an attaching clip may be received thereunder. The ends of the openings are defined by the curled tabs H which define substantially straight edges Hg and; curl within the pipe Hi to form a slot capable of receiving a clip of similar configuration;

The longitudinal edges. H of the openings 0 have marginal, central, indentations l.5a where thewall of the pipe. In. is slightly. depressed. 'I-heseindentatlons form indexing conformations with respect to the opening and provide, by means of! the user's sense... of feel, a method of orienting clips. tobe received. in the. holes. withoutactually sighting the. clips on the holes,

In. accordance with the present invention, the pipe I l); is placed in a supporting die which suriQllPQfi. he i 3. 5 l slightly r s it the, region where the. hole is to be formed. a. two-part die. suitable for this purpose is shown iriFigfure'sifi and 3 Inffigur 2 the die is shown eleyation without the pipe or punch in place. In Figure 3 one of the mating'parts of the die is shown in top planview.

The die comprises a age: complementary mating parts, It and III, which, when in the mated "condition of Figure 2, foi'm'a longitudinal pipe-receiving opening due to their opposed semicirculare mating bores [5a and- 180. A pair of mating rectangular openings are formed in the parts It and llalongthemating. edges and extendltothetcpedgas of the bores 16a. and [Ba to. define a punch-receiving slot transverse to ha pen n efi ed by h ar s. ia. and. lia These rectangular areindicatedat lEb we ency...

the openings lfib and lab the bore portionsfof. slightly reduced ecce'ntric's hape, lie and l8 c. When a pipe is posltionedin the die in the bore Lia-4. a, and clamped together by suitableclosin mechanism employing the necessary lateral force, these eccentric positions of the die distort the pipe and mm" its wall slightly into the slot formed by the opening I61) and lab, gripping the pipe with lateral pressure to prevent its distortion in the region. adjacent. the. slot and providing in the region to be. cutan upward. pressure to resist thapressur of the punch 20 sufficiently to insure the clean cut. desired.- The. vertical. diameter of the hole formed by the portions lie and lie may be. 1 .01. inches and the horizontal diameter 0.99 inch, where the outer. diameter of the pipe being punched is 1.0.0=,inch, for example.

The hole-forming punch 20 is shown in perspective in Figure 4, as. being of; rectangular cross-section andihaving. a generally V,-shaped cutting. face. In elevation the punch 20, has an initial cutting portion 20a formedat. anangle 01 about 30.- degreesto thelength of the punch. The cutting faceof the punchinthe-lesssharp y angled portions 20b and in some of the sharp portions 20a is of concave shape and may be so formed by suitable milling operations. In the region adjacent the cutting edge 200 at the apex of the initial cutting portion the depth of the concave portion is reduced so as to form the nearly straight cutting edge 20c.

Holes are punched by the apparatus above described by placing the pipe In between th pair of dies 1,6 and IB suggested in Figure 5, the lateral openings lib and lBb of the dies being located over the position desired for the opening. The punch 2|] is then placed in the slot formed by the openings I61) and l8b and forced downwardly as indicated by the arrow 22, this force being provided by a suitable press.

As the pinion IQ. is first forced down on the pipe I0 the edge 200 being of greater radius than the wall of the pipe, engages the wall of the pipe and depresses it along a nearly straight line. The. pipe then bends inwardly asshown at l5 before. actual cutting action begins. At this time th inwardly. bent or indented portion IQ of the pipe extends beyond the edges of the slot formed by the dies l6 and 18, thereby forming the indexing indentations l5a, Figure 1.

As the punch 20 is pressed further against the pipe lo, the punch parts. the wall of the pipe along the edge 20c, thereby forming a split edge transverse to the length of the opening. Fun ther pressure on the punch peels the pipe wall inwardly along this edge, the cutting action being made by the sharply angled edges formed on the portions 20b of the punch. When the punch has fully pierced the wall of the pipe, the edges have curled underneath as shown in Figure 1, leaving a free opening of the desired shape with cleanly punched longitudinal edges.

While I have shown the edge 200 as having a nearly straight configuration, it may be somewhat concave so long as it has a relatively large radius of curvature. in relation to theouter di.- ameter of the pipe l0.

While I have shown and described a specific embodiment of my invention, it will of coursebe understood that many modifications and alter! native constructions may be made without de-. partingfrom the spirit and scope thereof. I therefore intend by the appended claims to cover. all modifications and alternative constructions falling within the true spirit and scope thereof;

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A punch-and-die apparatus adapted to punch a rectangular aperture in a curvedmetal surface such as a pipe, the aperture to be formed with clean side edges substantially parallel to the axis of curvature and end edges substantially perpendicular thereto and formed byv inwardly bent tabs, comprising the combination of. a die defining a channeladapted to receive the metal surface snugly and to support the wall thereof anddefining also. a punch-receiving op nillt corresponding in shape to that of the desired aperture, and a punch adapted to be received in operative position in the punch-receiving opening, said punch having, an. initial cutting edge contained in a single plane substantially parpendicular to the axis of curvature of the metal surface. and being curved on a radius of; curvature. substantially, greater than the radius of curvature of the metal surface being punched; and having also secondary cutting. edges extending. away alongtheside walls. of said punchin 6 planes substantially parallel to the axis of cur- References Cited in the file of this patent vature. the cutting face 01' said punch being un- UNITED STATES PATENTS dercut between said secondary cutting edges to provide a concave surface therebetween. Number Name Date 2. Apparatus according to claim 1 wherein 5 483,648 Fischer 41 1892 said punch is provided with two sets of sym- 8401592 Stacy 1907 metrically formed secondary cutting edges dis- 352 gg osed on o osite sides 1 sad initial cuttin Edge. pp 1 g 2,555,069 Verney May 29, 1951 JOHN W. DOLBY. 10 

